FK506 promotes liver regeneration by suppressing natural killer cell activity

Fk506 Inhibit liver regeneration in HOC model Rat

BACKGROUND

Studies have shown that lymphocytes support hepatic oval cell (HOC)-dependent liver regeneration and FK506（Tacrolimus） is known as an immunosuppressor. Therefore, we studied the role of FK506 in HOC activation and/or proliferation to guide the clinical use of FK506.

METHODS

Thirty male Lewis rats were randomly divided into 4 groups: (A) intervene in activation (n = 8), (B) intervene in proliferation (n = 8), (C) control HOC model (n = 8), and (D) pure partial hepatectomy (PH) (n = 6). The HOC model was established by 2AAF(2-acetylaminofluorene)/PH in groups A to C. FK506 (at a dose of 1 mg/kg/d) was given subcutaneously in group A except on operation day, and not until day 8 post-operation (PO) in group B. Half of the animals were euthanized on days 10 and 14 PO, respectively. The remnant liver was weighed and stained by hematoxylin and eosin and immunohistochemical staining of proliferating cell nuclear antigen and epithelial cell adhesion molecule enabled HOC proliferation analysis.

RESULTS

FK506 intervention exacerbated liver damage and hindered the recovery of the HOC model rat. Weight gain was severely retarded or even negative. Liver weight and the liver body weight ratio were lower than control group. HE and immunohistochemistry showed pooer proliferation of hepatocytes and fewer HOC numbers in group A.

CONCLUSION

FK506 inhibited HOC activation by affecting T and NK cells, ultimately blocking liver regeneration. Poor liver regeneration after auxiliary liver transplantation might be associated with the inhibition of HOC activation and proliferation caused by FK506 treatment.

Liver Regeneration after Hepatectomy and Partial Liver Transplantation

The liver is a unique organ with an abundant regenerative capacity. Therefore, partial hepatectomy (PHx) or partial liver transplantation (PLTx) can be safely performed. Liver regeneration involves a complex network of numerous hepatotropic factors, cytokines, pathways, and transcriptional factors. Compared with liver regeneration after a viral- or drug-induced liver injury, that of post-PHx or -PLTx has several distinct features, such as hemodynamic changes in portal venous flow or pressure, tissue ischemia/hypoxia, and hemostasis/platelet activation. Although some of these changes also occur during liver regeneration after a viral- or drug-induced liver injury, they are more abrupt and drastic following PHx or PLTx, and can thus be the main trigger and driving force of liver regeneration. In this review, we first provide an overview of the molecular biology of liver regeneration post-PHx and -PLTx. Subsequently, we summarize some clinical conditions that negatively, or sometimes positively, interfere with liver regeneration after PHx or PLTx, such as marginal livers including aged or fatty liver and the influence of immunosuppression.

Tacrolimus Improves the Implantation Rate in Patients with Elevated Th1/2 Helper Cell Ratio and Repeated Implantation Failure (RIF)

Introduction An abnormal endometrial immune response is involved in the pathogenesis of repeated implantation failure (RIF), so we investigated the effectiveness of tacrolimus treatment on the endometrium of RIF patients.

Materials and Methods Ten RIF patients with elevated T-helper 1/T-helper 2 (Th1/Th2) cell ratios were recruited into a clinical study. The expression of p53, leukemia inhibitory factor (LIF), interleukin (IL)-4, IL-10, IL-17, and interferon gamma (IFN-γ) in the endometrium of patients with and without tacrolimus treatment and the association of these factors with assisted reproductive technology (ART) outcomes were investigated.

Results Tacrolimus significantly increased the expression of LIF, IL-10, and IL-17 and decreased the expression of IL-4, IFN-γ, and the IFN-γ/IL-10 ratio in RIF patients. Tacrolimus treatment resulted in an implantation rate of 40%, a clinical pregnancy rate of 50%, and a live birth rate of 35% in RIF patients with elevated Th1/Th2 ratios who had previously failed to become pregnant despite at least three transfers of embryos. We also found a significant positive correlation between IL-10 levels and the implantation rate.

Conclusions Our findings suggest that RIF patients with a higher Th1/Th2 ratio could be candidates for tacrolimus therapy and that this immunosuppressive drug could be acting through upregulation of LIF, IL-10, and IL-17.

Auxiliary xenotransplantation as an in vivo bioreactor-Development of a transplantable liver graft from a tiny partial liver

BACKGROUND

We established a completely novel method of auxiliary xenogeneic partial liver transplantation and examined whether liver grafts procured from Syrian hamsters regenerated in nude rats, which were used as in vivo bioreactors.

METHODS

The hamsters and the rats were all males (n = 10). Partial liver grafts from hamsters were transplanted into nude rats in an auxiliary manner. We evaluated liver graft injury, rejection, and regeneration during 7 days after auxiliary xenogeneic partial liver transplantation.

RESULTS

All rats survived until sacrifice on post-operative day (POD) 1, 3, and 7. HE-staining showed normal at POD1, mild periportal edema, and slight bile duct and venous endothelial inflammation at POD3, and moderate acute cellular rejection at POD7 without parenchymal necrosis. The liver regeneration rates at POD3 and 7 were 1.54 ± 0.23 and 2.54 ± 0.43, respectively. The Ki-67 labeling index was also elevated at POD3 (27.5 ± 4.1%). Serum HGF and VEGF were elevated at POD1 and 3. ATP levels of liver grafts recovered at POD7.

CONCLUSIONS

These results revealed that with appropriate immunosuppressive therapy, partial liver graft regeneration occurred in a xenogeneic animal, which suggests liver grafts regenerated in xenogeneic environments, such as an in vivo bioreactor, have potential to be transplantable liver grafts for humans.

Assessment of Effect of Intraperitoneal Tacrolimus on Liver Regeneration in Major (70%) Hepatectomy Model After Experimental Pringle Maneuver in Rats

AIM

Small-for-size grafts have become more important, especially in living donor liver transplants. The Pringle maneuver, used to reduce blood loss, and the immunosuppressive medications used to prevent graft rejection in liver transplants have different side effects on liver regeneration. We researched the effect of situations where tacrolimus and the Pringle maneuver were applied or not on liver regeneration in rats with partial hepatectomy.

MATERIAL AND METHODS

This study was completed with 35 Wistar Albino rats. The subjects were randomly divided into 5 groups: Group 1 had the abdomen opened and no other procedure was performed; Group 2 underwent a 70% hepatectomy; Group 3 underwent a 15-minute Pringle maneuver + 70% hepatectomy; Group 4 underwent a 70% hepatectomy + 5 days of 1 mg/kg/day intraperitoneal tacrolimus; and Group 5 underwent a 150 minute Pringle maneuver + 0% hepatectomy + 5 days of 1 mg/kg/day intraperitoneal tacrolimus. All rats were sacrificed on the seventh postoperative day, remaining liver tissue was weighed, and weight indices created. The remaining liver tissue was stained with phosphohistone H3 and the mitotic index calculated.

RESULTS

The groups that underwent the Pringle maneuver, 70% hepatectomy, and tacrolimus administration were compared with the control group in terms of mitotic index and weight index, but no statistically significant differences were identified.

CONCLUSION

Suppression of regeneration forms a risk after liver transplantation with small-volume grafts. As a result, research on the effect of tacrolimus combined with the Pringle maneuver is important, especially for transplantations using segmented liver grafts. In our study, we showed that the use of tacrolimus had no negative effect on liver regeneration.

The efficacy and safety of tacrolimus monotherapy in adult-onset nephrotic syndrome caused by idiopathic membranous nephropathy

Introduction: The purpose of the study is to evaluate the efficiency and safety of tacrolimus (TAC) monotherapy in the treatment of nephrotic idiopathic membranous nephropathy (IMN) compared with the protocol of cyclophosphamide (CTX) combined with corticosteroids.

Methods: In total, 58 patients with nephrotic syndrome and biopsy-proven IMN were included in this study. 30 patients received TAC monotherapy with an initial dose of 0.05–0.1 mg/kg/day. 28 patients received transvenous CTX at a dose of 0.5–0.75 g/m² once in every month initially for 6 months and once in every 2 or 3 months for the later period, and the regimen was combined with corticosteroids (prednisone 1 mg/kg/d). All patients were observed for the treatment effects, recurrence and side effects.

Results: Twelve months after the initial treatment, a total of 24 (80%) patients in the TAC group and 23 (82.1%) patients in the CTX group achieved remission (either partial or complete remission). The survival curve of the probability of remission and complete remission were similar between the two groups (p > .05). Proteinuria (based on 24 h urinary protein excretion) was significantly decreased, and serum albumin was significantly increased after immunosuppressive treatment in both the groups. Estimated glomerular filtration rate (eGFR) was comparable between before and after treatment. The main adverse effects in TAC treatment were glucose intolerance, diabetes and abnormal aminotransferase.

Conclusions: TAC monotherapy is an alternative therapeutic regimen for patients with nephrotic IMN. Its short-term efficiency and patient tolerance are both acceptable.

Liver natural killer cells: subsets and roles in liver immunity

The liver represents a frontline immune organ that is constantly exposed to a variety of gut-derived antigens as a result of its unique location and blood supply. With a predominant role in innate immunity, the liver is enriched with various innate immune cells, among which natural killer (NK) cells play important roles in host defense and in maintaining immune balance. Hepatic NK cells were first described as 'pit cells' in the rat liver in the 1970s. Recent studies of NK cells in mouse and human livers have shown that two distinct NK cell subsets, liver-resident NK cells and conventional NK (cNK) cells, are present in this organ. Here, we review liver NK cell subsets in different species, revisiting rat hepatic pit cells and highlighting recent progress related to resident NK cells in mouse and human livers, and also discuss the dual roles of NK cells in liver immunity.

TIGIT safeguards liver regeneration through regulating natural killer cell-hepatocyte crosstalk

Overactivation of innate immunity, particularly natural killer (NK) cells, is harmful to liver regeneration; however, the molecular mechanisms that limit NK cell overactivation during liver regeneration are still elusive. Here we show that a coinhibitory receptor, T cell Ig and ITIM domain (TIGIT), was selectively up-regulated on NK cells, along with high expression of its ligand, poliovirus receptor (PVR/CD155), on hepatocytes during liver regeneration. The absence of TIGIT impaired liver regeneration in vivo, along with overactivation of NK cells and higher NK-derived interferon-gamma (IFN-γ) production. We also show that both depletion of NK cells and deficiency of IFN-γ, but not deficiency of RAG1, rescued impaired liver regeneration caused by the absence of TIGIT. Adoptive transfer of Tigit(-/-) NK cells into NK-deficient Nfil3(-/-) mice sufficiently led to impairment of liver regeneration. On the other hand, silencing PVR in hepatocytes rescued impaired liver regeneration caused by TIGIT deficiency in vivo, while blockade of TIGIT in NK-hepatocyte coculture increased IFN-γ production by NK cells in vitro.

CONCLUSION

TIGIT is a safeguard molecule to improve liver regeneration through negatively regulating NK-hepatocyte crosstalk. This finding suggests a novel mechanism of NK cell self-tolerance towards regenerative hyperplasia of the host.

Sirolimus influence on hepatectomy-induced liver regeneration in rats

OBJECTIVE: To evaluate the influence of sirolimus on liver regeneration triggered by resection of 70% of the liver of adult rats. METHODS: we used 40 Wistar rats randomly divided into two groups (study and control), each group was divided into two equal subgroups according to the day of death (24 hours and seven days). Sirolimus was administered at a dose of 1mg/kg in the study group and the control group was given 1 ml of saline. The solutions were administered daily since three days before hepatectomy till the rats death to removal of the regenerated liver, conducted in 24 hours or 7 days after hepatectomy. Liver regeneration was measured by the KWON formula, by thenumber of mitotic figures (hematoxylin-eosin staining) and by the immunohistochemical markers PCNA and Ki-67. RESULTS: there was a statistically significant difference between the 24h and the 7d groups. When comparing the study and control groups in the same period, there was a statistically significant variation only for Ki-67, in which there were increased numbers of hepatocytes in cell multiplication in the 7d study group compared with the 7d control group (p = 0.04). CONCLUSION: there was no negative influence of sirolimus in liver regeneration and there was a positive partial effect at immunohistochemistry with Ki-67.

Effects of tacrolimus and insulin in a liver regeneration model in growing animals with portal vein stenosis: immunohistochemical and molecular studies

The aim of the present investigation was to describe a new model of liver regeneration in growing rats with reduced portal flow. In addition, it was studied whether tacrolimus and insulin could have any pro-regenerative effect under such conditions. Ninety-five rats were divided into five groups: Group 1 (sham), abdominal incision without intervention; Group 2, 70% hepatectomy; Group 3, 70% hepatectomy + PV stenosis; Group 4, 70% hepatectomy + portal vein stenosis + insulin; and Group 5, 70% hepatectomy + portal vein stenosis + tacrolimus. The remnant liver lobes were harvested for analyses. The liver weight decreased in the PV stenosis group and it increased with the use of insulin and tacrolimus. The mitotic activity was higher in the hepatectomy, insulin and tacrolimus groups and this parameter was reduced by portal stenosis. Levels of interleukin 6 (IL-6) were higher in the hepatectomy group compared to the sham and PV stenosis groups. The expression of IL-6 and Ki67 was significantly increased in the insulin and tacrolimus groups compared to the portal stenosis group. A highly reproducible model was standardized to study liver regeneration with portal blood inflow reduction in weaning rats. It was demonstrated that insulin or tacrolimus administration may partially reverse the harmful effects of PV stenosis.

Nonobese diabetic natural killer cells: a barrier to allogeneic chimerism that can be reduced by rapamycin

BACKGROUND

Induction of allogeneic hematopoietic chimerism is a promising strategy to induce tolerance to donor islets for treating type 1 diabetes. Successful induction of chimerism requires overcoming host alloimmunity. In diabetes-prone nonobese diabetic (NOD) mice, this is challenging due to their general tolerance resistance. Although the adaptive alloimmunity of NOD mice is a known barrier to allogeneic chimerism, whether NOD natural killer (NK) cells are an additional barrier has not been examined. Because NOD NK cells exhibit functional defects, they may not inhibit chimerism generation.

METHODS

Antibody depletion of NK cells in vivo, or transplantation of F1 hybrid donor cells to eliminate the "missing-self" trigger of NK cells, was preformed to test the NK-mediated rejection of donor bone marrow cells. We also studied the capacity of rapamycin to block the NK cell response against allogeneic cells in vivo.

RESULTS

Depleting NK cells or rendering them unresponsive to the donor greatly improved the level of chimerism obtained in NOD mice. Rapamycin significantly reduced the resistance to allogeneic chimerism mounted by NOD NK cells; however, it was much less effective than NK cell depletion by antibodies.

CONCLUSIONS

Contrary to the view that NOD NK cells are defective, we found these cells to be a substantial barrier to allogeneic chimerism in the presence or absence of adaptive immunity. Moreover, rapamycin will need to be combined with other approaches to fully overcome the NK cell barrier.

Progression to adenocarcinoma in Barrett's esophagus after liver transplantation

BACKGROUND

The risk for development of certain malignancies after transplantation is well known. Especially in premalignant lesions of the skin and colon, rapid progression is described. The aim of this study is to evaluate the progress of Barrett's mucosa to adenocarcinoma of the esophagus after liver transplantation.

METHODS

Between 2000 and 2009, 895 patients underwent a liver transplantation in our department. All patients had an upper endoscopy as part of the evaluation before transplantation. Patients who had Barrett's mucosa described in their endoscopy report were identified. The records of these patients were retrospectively reviewed.

RESULTS

There were seven patients who had Barrett's mucosa in the preoperative endoscopy. Five of these patients (71%) developed an esophageal adenocarcinoma in a median time of 66 months after liver transplantation. One had stage II disease and four had stage III disease. Three of them underwent neoadjuvant therapy. All patients underwent an en bloc esophagectomy. One patient developed recurrent disease after 12 months and died 37 months after esophagectomy. The other four patients are still alive without recurrence and have a median survival of 16 months.

CONCLUSION

Esophageal cancer after liver transplantation is rare, whereas the risk for progression of Barrett's esophagus to adenocarcinoma is extremely high. Surveillance endoscopy with aggressive endoscopic treatment of the Barrett's is essential for these patients to prevent them from cancer death. Furthermore, immunosuppression therapy based on immunosuppressants with antitumoral effects should be preferred. The esophagectomy with neoadjuvant therapy is also in immunosuppressant patients feasible without increased risk for complications.

Regulation of hepatocyte fate by interferon-γ

Interferon (IFN)-γ is a cytokine known for its immunomodulatory and anti-proliferative action. In the liver, IFN-γ can induce hepatocyte apoptosis or inhibit hepatocyte cell cycle progression. This article reviews recent mechanistic reports that describe how IFN-γ may direct the fate of hepatocytes either towards apoptosis or a cell cycle arrest. This review also describes a probable role for IFN-γ in modulating hepatocyte fate during liver regeneration, transplantation, hepatitis, fibrosis and hepatocellular carcinoma, and highlights promising areas of research that may lead to the development of IFN-γ as a therapy to enhance recovery from liver disease.

Safety profile of IBD: lymphoma risks

This article describes the cancer risks of commonly used inflammatory bowel disease (IBD) medications, with an emphasis on hematologic malignancy risks. The increasing use of immunosuppressant therapies in the treatment of IBD has raised this question to an even greater importance. Studies evaluating these medications are complicated due to varying disease severity and concomitant use of other immunosuppressant medication. The potential risks of all therapies must be weighed against the benefits these therapies can offer these patients.

Safety profile of IBD: lymphoma risks

This article describes the cancer risks of commonly used inflammatory bowel disease (IBD) medications, with an emphasis on hematologic malignancy risks. The increasing use of immunosuppressant therapies in the treatment of IBD has raised this question to an even greater importance. Studies evaluating these medications are complicated due to varying disease severity and concomitant use of other immunosuppressant medication. The potential risks of all therapies must be weighed against the benefits these therapies can offer these patients.

Liver natural killer and natural killer T cells: immunobiology and emerging roles in liver diseases

Hepatic lymphocytes are enriched in NK and NKT cells that play important roles in antiviral and antitumor defenses and in the pathogenesis of chronic liver disease. In this review, we discuss the differential distribution of NK and NKT cells in mouse, rat, and human livers, the ultrastructural similarities and differences between liver NK and NKT cells, and the regulation of liver NK and NKT cells in a variety of murine liver injury models. We also summarize recent findings about the role of NK and NKT cells in liver injury, fibrosis, and repair. In general, NK and NKT cells accelerate liver injury by producing proinflammatory cytokines and killing hepatocytes. NK cells inhibit liver fibrosis via killing early-activated and senescent-activated stellate cells and producing IFN-gamma. In regulating liver fibrosis, NKT cells appear to be less important than NK cells as a result of hepatic NKT cell tolerance. NK cells inhibit liver regeneration by producing IFN-gamma and killing hepatocytes; however, the role of NK cells on the proliferation of liver progenitor cells and the role of NKT cells in liver regeneration have been controversial. The emerging roles of NK/NKT cells in chronic human liver disease will also be discussed.Understanding the role of NK and NKT cells in the pathogenesis of chronic liver disease may help us design better therapies to treat patients with this disease.

Both tacrolimus and sirolimus decrease Th1/Th2 ratio, and increase regulatory T lymphocytes in the liver after ischemia/reperfusion

The protective effects of immunosuppressants against ischemia/reperfusion (I/R) injury have been attributed to their non-specific anti-inflammatory effect. However, these effects may also depend on their effect on T lymphocytes, which are increasingly considered to be key players in I/R. Here, we studied the effects of tacrolimus and sirolimus on lymphocyte subpopulations in an I/R rat model. The animals were treated with tacrolimus, sirolimus or vehicle, before undergoing a 60-min ischemia event of the right hepatic lobe, followed by excision of the remaining liver. After 2 h, I/R rats showed increased mortality, plasma lactate dehydrogenase (LDH) levels, hepatocyte apoptosis, liver histological injury and parenchymal infiltration by neutrophils, macrophages, NK cells and T lymphocytes. Most of the changes were antagonized by both immunosuppressants. Tacrolimus augmented the proportion of cycling cells in I/R rats, whereas sirolimus showed the opposite effect. The increased Th1/Th2 ratio found in I/R livers after 2 h was reverted by immunosuppressants, which also amplified the proportion of CD4(+)CD25(+)Foxp3(+) regulatory T lymphocytes at 24 h. The protective effects of both tacrolimus and sirolimus correlated well with a decreased ratio of proinflammatory to anti-inflammatory T lymphocytes, and with an increase in the Treg proportion. This suggests a new mechanism to explain the known beneficial effect shown by immunosuppressants early after I/R.

Zinc finger protein A20 promotes regeneration of small-for-size liver allograft and suppresses rejection and results in a longer survival in recipient rats

BACKGROUND

Small-for-size liver allografts without immunosuppression have decreased survival compared with full-for-size grafts for the concomitant regeneration-induced accelerated rejection. This study was designed to examine the effect of zinc finger protein A20 on liver allograft regeneration and acute rejection using a high responder rat model (DA-->Lewis) of 30% partial liver transplantation.

MATERIALS AND METHODS

Adenovirus carrying the full length of A20 was introduced into liver grafts by ex vivo perfusion via the portal vein during preservation, physiological saline (PS), and empty Ad vector rAdEasy served as controls; then small-sized liver transplants were performed. Liver graft regeneration was assessed, as well as graft rejection, hepatocyte apoptosis, nuclear factor kappa B activation, and intercellular adhesion molecule-1 mRNA expression in liver graft sinusoidal endothelial cells (LSECs), infiltration of liver graft infiltrating mononuclear cells (LIMCs), and the subproportion of NK and NKT cells, activity of liver graft NK-like cells, interferon gamma (IFN-gamma) production, and animal survival.

RESULTS

Ex vivo transfer of the A20 gene resulted in overexpression of A20 protein in LSECs and hepatocytes 24 h after partial liver transplantation. Regeneration of the small-sized liver allograft was augmented by A20 overexpression, the DNA synthesis of hepatocytes on d 4 post-transplant was increased in A20 group compared with PS and rAdEasy groups (P < 0.01). Hepatocyte apoptosis was inhibited by A20 (P < 0.001). On d 4 after transplantation, histological examination revealed a more exiguous cellular infiltration and mild rejection in A20 group but a more vigorous cellular infiltration in the sinusoidal area and more severe rejection in PS and rAdEasy group. Nuclear factor kappa B activation and intercellular adhesion molecule-1 mRNA expression in LSECs were suppressed by A20 overexpression. Flow cytometry analysis showed a marked down-regulation of LIMCs number by A20, including more prominent decrease in the subproportion of NK and NKT cells. Activity of liver graft NK-like cells, IFN-gamma mRNA expression in LIMCs, and serum IFN-gamma protein level were also suppressed by A20 overexpression (P < 0.05), respectively. Survival days of A20 rats were longer than those of PS rats and rAdEasy rats (P < 0.01), whereas survival days of rAdEasy rats were shorter than those of PS rats (P < 0.01).

CONCLUSIONS

These data suggest that A20 overexpression could effectively promote small-sized liver allograft regeneration, suppress rejection, and prolong survival of recipient rat. These effects of A20 could be related to an inhibition of LSECs activation, suppression of infiltration of LIMCs, and the subpopulations such as NK and NKT cells into liver graft, and inhibition of hepatocyte apoptosis.

Effect of the immunosuppressants on hepatocyte proliferation and apoptosis in a young animal model of liver regeneration: an immunohistochemical study using tissue microarrays

Hepatocyte proliferation and apoptosis (programmed cell death) occur during the liver parenchyma regeneration and the liver size modeling is mainly controlled by hepatocyte apoptosis. The purpose of the present study was to verify the influence of immunosuppressant drugs on these phenomena by utilizing tissue microarray techniques. Thirty-six weaning rats (age 21-23 days, weight 30-50 g) were divided into six groups: control, sham, hepatectomy, hepatectomy plus solumedrol, hepatectomy plus CsA, and hepatectomy plus Tac. The animals were killed one day after hepatectomy, and the remnant livers were weighed and harvested for tissue microarray sections. Liver cell proliferation was evaluated by staining for PCNA and apoptosis was detected by the TUNEL method. It was verified that CsA promoted a decrease in the liver weight, Tac and CsA decreased the proliferation index of hepatocytes, and glucocorticoid had no significant effects. The apoptosis index was not altered by hepatectomy or immunosuppressants. Our data indicate that, in the growing rat, CsA and Tac have negative effects on hepatocyte proliferation and have no effect on the hepatocyte apoptosis.

Effect of the immunosuppressants on hepatocyte cells proliferation and apoptosis during liver regeneration after hepatectomy - molecular studies

The regeneration and remodeling of the transplanted liver is the result of hepatocyte proliferation and apoptosis (programmed cell death). The purpose of this study was to verify the influence of immunosuppressants on the expression levels of genes: IL-6 (regulator of hepatocyte proliferation), pro-apoptotic (Bak and Bax) and anti-apoptotic (Bcl-Xl and Bcl-2). 36 newborn suckling rats (age 5-7 days, weight 6-10 g) were divided into four groups: hepatectomy, hepatectomy plus methylprednisolone, hepatectomy plus CsA and hepatectomy plus Tac. The same experiments were performed in 24 weaning rats (age 21-23 days, weight 30-50 g). The animals were killed one day after the hepatectomy and the remnant livers were analyzed. The livers of all animals exhibited histological changes of liver regeneration. The immunosuppressants did not promote any alteration on IL-6 gene expression levels. Methylprednisolone and CsA increased the expression levels of Bak gene in newborn rats. However, methylprednisolone and Tac promoted increased expression levels of Bcl-2 in all groups. We hypothesize that these effects explain the efficacy of these drugs on the treatment of acute and chronic liver rejection as the expression of Bcl-2 in cholangiocytes is decreased as a consequence of bile duct lesions

Changes in circulating cytokine levels and lymphocyte subsets in healthy liver donors after partial hepatectomy

AIM

Studies of animal models have determined that liver regeneration after partial hepatectomy is mediated by a various cytokines. The aim of the present study was to evaluate the levels of these cytokines and subsets of circulating lymphocytes in healthy humans after partial hepatectomy.

METHODS

Four individuals underwent partial hepatectomy for living-related donor liver transplantation. We also evaluated for comparison, three patients with myoma uteri who underwent hysterectomy. Blood samples were obtained before surgery and on postoperative days (PD) 1, 3, and 7. Serum levels of hepatocyte growth factor, interleukin (IL)-6, -10, and plasma levels of transforming growth factor beta were measured.

RESULTS

Increased circulating levels of hepatocyte growth factor and transforming growth factor beta were observedafter hepatectomy. The levels of IL-6 and IL-10 peaked on PD 1. Circulating white blood cell counts increased remarkably, whereas lymphocyte count decreased particularly on PD 1 and 3. CD4/CD8 and T-helper cell (Th)1/Th2 ratios were still decreased on PD 7. The percentage of natural killer cells was increased on PD 1. Partial hepatectomy in healthy humans leads not only to decreased lymphocyte counts, but also to remarkable changes in lymphocyte subsets.

CONCLUSION

These findings suggest that immune suppression after partial hepatectomy involves decreases in CD4(+) helper T cells, particularly Th1 cells.

Tacrolimus depresses local immune cell infiltration but fails to reduce cortical contusion volume in brain-injured rats

The immunosuppressant drug tacrolimus (FK-506) failed to show an anti-edematous effect despite suppressing pro-inflammatory cytokines in cerebrospinal fluid following focal traumatic brain injury. By questioning the role of the inflammatory response as a pharmacological target, we investigated the effects of FK-506 on immune cell infiltration in brain-injured rats. Following induction of a cortical contusion, male Sprague-Dawley rats received FK-506 or physiological saline intraperitoneally. Brains were removed at 24 h, 72 h or 7 days, respectively. Frozen brain sections (7 microm) were stained immunohistologically for markers of endothelial activation (intercellular adhesion molecule-1--ICAM-1), neutrophil infiltration (His-48), and microglial and macrophage activation (Ox-6; ED-1), respectively. Immunopositive cells were counted microscopically. Contusion volume (CV) was quantified morphometrically 7 days after trauma. Inflammatory response was confined to the ipsilateral cortex and hippocampal formation, predominating in the contusion and pericontusional cortex. Strongest ICAM-1 expression coincided with sustained granulocyte accumulation at 72h which was suppressed by FK-506. Ox-6+ cells prevailing at 72 h were also significantly reduced by FK-506. ED-1+ cells reaching highest intensity at 7 days were significantly attenuated at 72 h. Cortical CV was not influenced. FK-506 significantly decreased post-traumatic local inflammation which, however, was not associated with a reduction in cortical CV. These results question the importance of post-traumatic local immune cell infiltration in the secondary growth of a cortical contusion.

Immunosuppression using the mTOR inhibition mechanism affects replacement of rat liver with transplanted cells

Successful grafting of tissues or cells from mismatched donors requires systemic immunosuppression. It is yet to be determined whether immunosuppressive manipulations perturb transplanted cell engraftment or proliferation. We used syngeneic and allogeneic cell transplantation assays based on F344 recipient rats lacking dipeptidyl peptidase IV enzyme activity to identify transplanted hepatocytes. Immunosuppressive drugs used were tacrolimus (a calcineurin inhibitor) and its synergistic partners, rapamycin (a regulator of the mammalian target of rapamycin [mTOR]) and mycophenolate mofetil (an inosine monophosphate dehydrogenase inhibitor). First, suitable drug doses capable of inducing long-term survival of allografted hepatocytes were identified. In pharmacologically effective doses, rapamycin enhanced cell engraftment by downregulating hepatic expression of selected inflammatory cytokines but profoundly impaired proliferation of transplanted cells, which was necessary for liver repopulation. In contrast, tacrolimus and/or mycophenolate mofetil perturbed neither transplanted cell engraftment nor their proliferation. Therefore, mTOR-dependent extracellular and intracellular mechanisms affected liver replacement with transplanted cells. In conclusion, insights into the biological effects of specific drugs on transplanted cells are critical in identifying suitable immunosuppressive strategies for cell therapy.

Liver pathology and cell proliferation after calcineurin inhibitors and antiproliferative drugs following partial hepatectomy in rats

Immunosuppressants are the cornerstones of treatment after solid organ transplantation. This study investigated the pathology and cell proliferation following partial hepatectomy (PH) in rats undergoing immunosuppressive treatment. After 1 day, all rats were subjected to 70% PH. Groups A and B (n = 10) received calcineurin inhibitors subcutaneously: either FK506 or cyclosporine (CyA). Groups C and D (n = 10) received antiproliferative drugs: either mycophenolate mofetil (MMF) or sirolimus (SRL) by gavage. A control group (n = 5) received 1 mL of tap water daily. On postoperative day 2, all rats were sacrificed to obtain liver tissue for pathologic examination. Using immunohistochemistry we separately examined the hepatectomy surface and the liver parenchyma. In the parenchyma, the Ki-67 indices were higher in the CyA and FK506 groups and lower in the SRL and MMF groups compared with controls (P < .01). CyA had the highest and MMF the lowest values. On the hepatectomy surface, Ki-67 indices and TGF-alpha expressions were higher in the CyA group and lower in the SRL and MMF groups compared with the control group (P < .01). Slightly higher values in the FK506 group were not significantly different compared with the control group (P > .05). All groups other than FK506 showed prominent cholangiolar epithelial phenotypes compared with the control group. In the CyA and SRL groups, the number of cholangiolar cells was higher (P < .01), and in the MMF group lower than in the control group (P < .01). Among all groups, SRL had the highest values.

Facilitation of Survival in a Rat Fulminant Hepatic Failure Model by Combination Therapy Using Recombinant G-CSF and Tacrolimus

The mortality rate of fulminant hepatic failure (FHF) is high because of retarded liver regeneration. Recombinant human granulocyte colony-stimulating factor (rHuG-CSF) and tacrolimus are known to be immunosuppressive and supportive to liver regeneration. We investigated the effects of their combination therapy in a rat FHF model with a 68% partial hepatectomy and 24% liver necrosis. All rats without drug pretreatment died within 55 h. The median time was prolonged from 37 to 52 h by rHuG-CSF (250 microg/kg/day s.c. on days -5 to 0) and to 46 h by tacrolimus (0.5 mg/kg/day i.m. on days -2 to 0). Notably, the combination therapy facilitated DNA biosynthesis and survival prolongation, with a median of 77 h. The interferon-gamma (IFN-gamma) protein levels and natural killer cell (NK) activity in the liver were low at 12 h, and no further inhibition was detected by any treatment. Tacrolimus significantly upregulated the mRNA levels of insulin receptors and transforming growth factor-alpha (TGF-alpha), whereas rHuG-CSF did not. Regarding tissue remodeling-related factors, rHuG-CSF upregulated mRNA levels of vascular endothelial growth factor (VEGF) and matrix metalloproteinase- 9 (MMP-9), whereas tacrolimus did not. The combination treatment upregulated protein levels of both insulin receptors and VEGF. These results suggest that tacrolimus improves the hepatocyte replication and rHuG-CSF contributes to tissue reconstitution, and this combination therapy directly facilitates liver regeneration in the FHF model.

Malignancy after transplantation

As newer immunosuppressive regimens have steadily reduced the incidence of acute rejection and have extended the life expectancy of allograft recipients, posttransplant malignancy has become an important cause of mortality. In fact, it is expected that cancer will surpass cardiovascular complications as the leading cause of death in transplant patients within the next 2 decades. An understanding of the underlying pathobiology and how to minimize cancer risks in transplant recipients are essential. The etiology of posttransplant malignancy is believed to be multifactorial and likely involves impaired immunosurveillance of neoplastic cells as well as depressed antiviral immune activity with a number of common posttransplant malignancies being viral-related. Although calcineurin inhibitors and azathioprine have been linked with posttransplant malignancies, newer agents such as mycophenolate mofetil and sirolimus have not and indeed may have antitumor properties. Long-term data are needed to determine if the use of these agents will ultimately lower the mortality due to malignancy for transplant recipients.

Negative regulation of liver regeneration by innate immunity (natural killer cells/interferon-gamma)

BACKGROUND AND AIMS

Hepatic lymphocytes are composed mainly of natural killer (NK) cells and NKT cells, which play key roles in innate immune responses against pathogens and tumors in the liver. This report analyzes the effects of activation of innate immunity by viral infection or the toll-like receptor 3 (TLR3) ligand on liver regeneration.

METHODS

The partial hepatectomy (PHx) method was used as a model of liver regeneration. Murine cytomegalovirus (MCMV) infection and the TLR3 ligand polyinosinic-polycytidylic acid [poly(I:C)] were used to activate innate immunity.

RESULTS

NK cells are activated after PHx, as evidenced by producing interferon (IFN)-gamma. Infection with MCMV or injection of poly(I:C) further activates NK cells to produce IFN-gamma and attenuates liver regeneration in the PHx model. Depletion of NK cells or disruption of either the IFN-gamma gene or the IFN-gamma receptor gene enhances liver regeneration and partially abolishes the negative effects of MCMV and polyI:C on liver regeneration, whereas NKT cells may only play a minor role in suppression of liver regeneration. Adoptive transfer of IFN-gamma +/+ NK cells, but not IFN-gamma -/- NK cells, restores the ability of polyI:C to attenuate liver regeneration in NK-depleted mice. Finally, administration of polyI:C or IFN-gamma enhances expression of several antiproliferative proteins, including STAT1, IRF-1, and p21cip1/waf1 in the livers of partially hepatectomized mice.

CONCLUSIONS

Our findings suggest that viral infection and the TLR3 ligand negatively regulate liver regeneration via activation of innate immunity (NK/IFN-gamma), which may play an important role in the pathogenesis of viral hepatitis.

Augmented regeneration of partial liver allograft induced by nuclear factor-kappaB decoy oligodeoxynucleotides-modified dendritic cells

AIM

To investigate the effect of NF-kappaB decoy oligodeoxynuleotides (ODNs) - modified dendritic cells (DCs) on regeneration of partial liver allograft.

METHODS

Bone marrow (BM)- derived DCs from SD rats were propagated in the presence of GM-CSF or GM-CSF+IL-4 to obtain immature DCs or mature DCs, respectively. GM-CSF-propagated DCs were treated with double-strand NF-kappaB decoy ODNs containing two NF-kappaB binding sites or scrambled ODNs. Allogeneic (SD rat to LEW rat) 50% partial liver transplantation was performed. Normal saline (group A), GM-CSF -propagated DCs (group B), GM-CSF+IL-4 - propagated DCs (group C), and GM-CSF+NF-kappaB decoy ODNs (group D) or scrambled ODNs -propagated DCs (group E) were injected intravenously into recipient LEW rats 7 days prior to liver transplantation and immediately after transplantation. DNA synthesis (BrdU labeling) and apoptosis of hepatocytes were detected with immunostaining and TUNEL staining postoperative 24 h, 48 h, 72 h and 84 h, respectively. Liver graft-resident NK cell activity, hepatic IFN-gamma mRNA expression and recipient serum IFN-gamma level at the time of the maximal liver allograft regeneration were measured with (51)Cr release assay, semiquantitative RT-PCR and ELISA, respectively.

RESULTS

Regeneration of liver allograft was markedly promoted by NF-kappaB decoy ODNs-modified immature DCs but was significantly suppressed by mature DCs, the DNA synthesis of hepatocytes peaked at postoperative 72 h in group A, group B and group E rats, whereas the DNA synthesis of hepatocytes peaked at postoperative 84 h in group C rats and 48 h in group D rats, respectively. The maximal BrdU labeling index of hepatocytes in group D rats was significantly higher than that in the other groups rats. NF-kappaB decoy ODNs-modified immature DCs markedly suppressed but mature DCs markedly promoted apoptosis of hepatocytes, liver-resident NK cell activity, hepatic IFN-gamma mRNA expression and recipient serum IFN-gamma production. At the time of the maximal regeneration of liver allograft, the minimal apoptosis of hepatocytes, the minimal activity of liver-resident NK cells, the minimal hepatic IFN-gamma mRNA expression and serum IFN-gamma production were detected in group D rats. The apoptotic index of hepatocytes, the activity of liver- resident NK cells, the hepatic IFN-gamma mRNA expression level and the serum IFN-gamma level in group D rats were significantly lower than that in the other groups rats at the time of the maximal regeneration of liver allograft.

CONCLUSION

The data suggest that the augmented regeneration of partial liver allograft induced by NF-kappaB decoy ODNs-modified DCs may be attributable to the reduced apoptotic hepatocytes, the suppressed activity of liver-resident NK cells and the reduced IFN-gamma production.

DNA immunization of the grafted liver by particle-mediated gene gun1

BACKGROUND

Direct DNA vaccination of liver allografts before transplantation may provide an effective strategy for inducing protective immunity to infection and malignancy.

METHODS

In this study, the authors examined the feasibility of gene gun-mediated vaccination of liver grafts. Using plasmids expressing luciferase and green fluorescent proteins, their expression was tested in a graft liver.

RESULTS

Protein expression was observed in the graft liver and significantly enhanced in hepatectomized rats. A short course of tacrolimus (FK506) also evoked the expression of these proteins. Effects of primary immunization to the liver on the humoral response were then tested using an expression plasmid encoding hepatitis B virus surface (HBs) antigen and were compared to that of skin immunization alone. The results showed that local immunization to the liver strongly induced antibody formation. Furthermore, the combination of an immunized partial liver graft with tacrolimus significantly enhanced antibody production against HBs antigen.

CONCLUSIONS

A DNA vaccine to the liver may be one strategy for preventing infectious disease associated with liver transplantation under tacrolimus treatment.

Hepatic T cells and liver tolerance

The T-cell biology of the liver is unlike that of any other organ. The local lymphocyte population is enriched in natural killer (NK) and NKT cells, which might have crucial roles in the recruitment of circulating T cells. A large macrophage population and the efficient trafficking of dendritic cells from sinusoidal blood to lymph promote antigen trapping and T-cell priming, but the local presentation of antigen causes T-cell inactivation, tolerance and apoptosis. These local mechanisms might result from the need to maintain immunological silence to harmless antigenic material in food. The overall bias of intrahepatic T-cell responses towards tolerance might account for the survival of liver allografts and for the persistence of some liver pathogens.

Effects of tacrolimus on hemispheric water content and cerebrospinal fluid levels of glutamate, hypoxanthine, interleukin-6, and tumor necrosis factor-α following controlled cortical impact injury in rats

Object. Disturbance of calcium homeostasis contributes to evolving tissue damage and energetic impairment following traumatic brain injury (TBI). Calcium-mediated activation of calcineurin results in production of tissue-damaging nitric oxide and free oxygen radicals. Inhibition of calcineurin induced by the immunosuppressant tacrolimus (FK506) has been shown to reduce structural and functional damage after ischemia. The aims of the present study were to investigate time- and dose-dependent short-term antiedematous effects of tacrolimus following TBI.

Methods. A left temporoparietal contusion (controlled cortical impact injury [CCII]) was induced in 51 male Sprague—Dawley rats. Tacrolimus (1 or 3 mg/kg body weight) was administered by a single intraperitoneal injection at 5 minutes, 30 minutes, or 4 hours after CCII occurred. Control rats received physiological saline. Water contents of traumatized and nontraumatized hemispheres, as well as cerebrospinal fluid (CSF) levels of mediators reflecting tissue damage (the proinflammatory cytokines interleukin [IL]-6 and tumor necrosis factor [TNF]—α, the excitotoxin glutamate, and the adenosine triphosphate—degradation product hypoxanthine), were determined 24 hours after trauma.

Although CSF levels of IL-6 and TNFα were completely suppressed by tacrolimus at all time points and at both concentrations, CSF levels of glutamate and hypoxanthine, as well as edema formation, were only marginally influenced. Significant reduction of cerebral water content was confined to nontraumatized hemispheres. In addition, the higher dose of tacrolimus failed to exert significant antiedematous effects on traumatized hemispheres.

Conclusions. Under the present study design, the potency of tacrolimus in reducing edema formation following CCII seems limited. However, its immunosuppressive effects could be of value in influencing the posttraumatic inflammatory response known to aggravate tissue damage.

Regenerative capacities of normal and cirrhotic livers following 70% hepatectomy in rats and the effect of alpha-tocopherol on cirrhotic regeneration

BACKGROUND

The regeneration of normal and cirrhotic liver has been very well demonstrated after partial hepatectomy; although the tissue regenerated by cirrhotic liver is also cirrhotic. The structural differences of the regenerated tissues between normal and cirrhotic livers may also indicate different regeneration capacities. The objective of this study was to compare the regeneration capacities of normal and cirrhotic livers by bromodeoxyuridine (BrdU) incorporation and proliferating cell nuclear antigen (PCNA) labeling indices in replicating nuclei and mitotic figures in cells in partially hepatectomized normal and cirrhotic rats and to study the effect of alpha-tocopherol on cirrhotic liver regeneration.

METHODS

Five groups of adult Wistar rats comprised normal livers, cirrhotic livers, regenerated normal livers, regenerated cirrhotic livers, and alpha-tocopherol-treated regenerated cirrhotic livers. Cirrhosis was induced by intragastric administration of carbon tetrachloride and phenobarbital in the drinking water of the rats. Liver regeneration capacities in normal and cirrhotic rats and following partial hepatectomy in normal and cirrhotic rats and cirrhotic rats that were administered alpha-tocopherol were evaluated through BrdU incorporation, PCNA labeling, and mitotic indices.

RESULTS

BrdU and PCNA labeling and mitotic indices were zero for normal rats and 4.3 +/- 3.5, 6.5 +/- 5, and 2.5 +/- 1.5 for cirrhotic rats, respectively. The values after partial hepatectomy in normal and cirrhotic rats were 46.2 +/- 8.7 and 27.8 +/- 7.5 for BrdU labeling, 83.7 +/- 6.5 and 51.3 +/- 6.8 for PCNA labeling, and 31.8 +/- 4.2 and 18.6 +/- 3.4 for mitotic index, respectively. For the fifth group comprising cirrhotic rats that were administered alpha-tocopherol and had undergone partial hepatectomy, BrdU incorporation, PCNA labeling, and mitotic indices were 37.5 +/- 6.3, 76.5 +/- 6.2, and 27.2 +/- 4.2, respectively. When the cirrhotic liver regeneration group was compared with the normal liver regeneration group, rates of liver regeneration in the cirrhotic group were significantly depressed (P < 0.01). Although the BrdU incorporation and PCNA labeling indices of the alpha-tocopherol-administered cirrhotic liver regeneration group indicated significantly lower rates of liver regeneration when compared with the normal liver regeneration group (P < 0.05), the liver regeneration rates of the alpha-tocopherol-administered cirrhotic group were also significantly higher than those of the cirrhotic liver regeneration group that was not administered alpha-tocopherol (P < 0.01).

CONCLUSIONS

Cirrhotic livers revealed a significantly depressed capacity for regeneration following partial hepatectomy. alpha-Tocopherol administration seemed to improve the rates of regeneration in cirrhotic rats with respect to the BrdU incorporation, PCNA labeling, and mitotic indices.

Enhanced migration and fusion of donor myoblasts in dystrophic and normal host muscle

Sliced male C57Bl/10Sn (H2-b) donor muscles were grafted into the female histocompatible muscles of untreated, FK506-treated, and T-cell depleted (with or without thymic tolerization) dystrophic (mdx; H2-b) and normal (C57Bl/10Sn; H2-b) hosts, and also into histoincompatible normal (Balb/c; H2-d) hosts. The fate of male donor nuclei was monitored on tissue sections by in situ hybridization with a Y-chromosome specific probe. The results demonstrate that the dystrophic environment is more conducive than normal muscle to donor myoblast migration, with the distance moved being threefold greater at 12 weeks in dystrophic hosts. T-cell depletion was significantly more effective than FK506 treatment at enhancing donor myoblast emigration in both histocompatible and histoincompatible hosts at 3 weeks. Furthermore, the effects of T-cell depletion were sustained in histoincompatible hosts at 12 weeks. These data endorse the use of host T-cell depletion as a promising long-term strategy to improve myoblast transfer therapy (MTT) in the clinical situation.